Abbreviation modalities of nitrogen multiple-breath washout tests in school children with obstructed lung disease

TY - JOUR

T1 - Abbreviation modalities of nitrogen multiple-breath washout tests in school children with obstructed lung disease

AU - Green, Kent

AU - Ejlertsen, Jacob S

AU - Madsen, Astrid

AU - Buchvald, Frederik F

AU - Kongstad, Thomas

AU - Kobbernagel, Helene

AU - Gustafsson, Per M

AU - Nielsen, Kim G.

N1 - © 2015 Wiley Periodicals, Inc.

PY - 2016/6/1

Y1 - 2016/6/1

N2 - Rationale: Nitrogen multiple-breath washout (N2 MBW) is a promising tool for assessing early lung damage in children with chronic obstructive pulmonary disease, but it can be a time-consuming procedure. We compared alternative test-shortening endpoints with the most commonly reported N2 MBW outcome, the lung clearance index, calculated as lung volume turnovers required to reach 2.5% of the starting N2 concentration (LCI2.5). Methods: Cross-sectional study of triplicate N2 MBW measurements obtained in cystic fibrosis (CF) patients (N = 60), primary ciliary dyskinesia (PCD) patients (N = 28), and matched healthy controls (N = 48) aged 5-18 years. Bland-Altman analysis was used to compare LCI2.5 with earlier LCI endpoints (3%, 4%, 5%, 7%, and 9% of starting N2 concentration), Cn@TO6 (defined as % of N2 starting concentration when reaching six lung volume turnovers), and LCI derived from only two N2 MBW runs in each session. N2 MBW endpoints were analyzed as z-scores calculated from healthy controls. Results: In PCD, Cn@TO6 and LCI2.5 exhibited similar values (mean [95%CI] difference: 0.33 [-0.24; 0.90] z-scores), reducing the test duration by one-third (5.4 min; 95%CI: 4.0; 6.8). All other tested alternative endpoints exhibited increasing disagreement with increasing LCI2.5. With an average reduction in test duration of 40%, LCI2.5 derived from two runs exhibited good agreement in all children. Conclusions: Cn@TO6 may be suggested as a potential test-shortening endpoint in school children with PCD. In CF, early test termination may reduce measurement power with advancing pulmonary disease, suggesting differences in underlying pathophysiology. Two technically acceptable N2 MBW runs may be sufficient in school children irrespective of diagnosis with CF or PCD.

AB - Rationale: Nitrogen multiple-breath washout (N2 MBW) is a promising tool for assessing early lung damage in children with chronic obstructive pulmonary disease, but it can be a time-consuming procedure. We compared alternative test-shortening endpoints with the most commonly reported N2 MBW outcome, the lung clearance index, calculated as lung volume turnovers required to reach 2.5% of the starting N2 concentration (LCI2.5). Methods: Cross-sectional study of triplicate N2 MBW measurements obtained in cystic fibrosis (CF) patients (N = 60), primary ciliary dyskinesia (PCD) patients (N = 28), and matched healthy controls (N = 48) aged 5-18 years. Bland-Altman analysis was used to compare LCI2.5 with earlier LCI endpoints (3%, 4%, 5%, 7%, and 9% of starting N2 concentration), Cn@TO6 (defined as % of N2 starting concentration when reaching six lung volume turnovers), and LCI derived from only two N2 MBW runs in each session. N2 MBW endpoints were analyzed as z-scores calculated from healthy controls. Results: In PCD, Cn@TO6 and LCI2.5 exhibited similar values (mean [95%CI] difference: 0.33 [-0.24; 0.90] z-scores), reducing the test duration by one-third (5.4 min; 95%CI: 4.0; 6.8). All other tested alternative endpoints exhibited increasing disagreement with increasing LCI2.5. With an average reduction in test duration of 40%, LCI2.5 derived from two runs exhibited good agreement in all children. Conclusions: Cn@TO6 may be suggested as a potential test-shortening endpoint in school children with PCD. In CF, early test termination may reduce measurement power with advancing pulmonary disease, suggesting differences in underlying pathophysiology. Two technically acceptable N2 MBW runs may be sufficient in school children irrespective of diagnosis with CF or PCD.

KW - Adolescent

KW - Breath Tests

KW - Child

KW - Child, Preschool

KW - Cross-Sectional Studies

KW - Cystic Fibrosis

KW - Female

KW - Functional Residual Capacity

KW - Humans

KW - Lung

KW - Lung Diseases, Obstructive

KW - Male

KW - Nitrogen Dioxide

KW - Prospective Studies

KW - Respiratory Function Tests

KW - Tidal Volume

KW - Total Lung Capacity

KW - Journal Article

U2 - 10.1002/ppul.23339

DO - 10.1002/ppul.23339

M3 - Journal article

C2 - 26595237

SN - 1054-187X

VL - 51

SP - 624

EP - 632

JO - Pediatric pulmonology. Supplement

JF - Pediatric pulmonology. Supplement

IS - 6

ER -